Free Iron Testing
Free iron testing identifies free iron on metal surfaces, most often on nickel and stainless steel, where surface contamination makes materials more corrosion-prone and shortens their service life.
Field / On-Site
Ferroxyl · Copper sulfate
Nickel · stainless steel
Surface iron contamination
What it is
Free iron testing is used to identify free iron on a metal surface. This test is mainly performed on nickel and stainless steel, where iron contamination left from fabrication, tooling, or handling can compromise an otherwise corrosion-resistant surface.
Why it matters
The presence of free iron on a metal surface makes the material more corrosion-prone and reduces its lifespan. Testing verifies material quality and enables more accurate predictions about how long a component will perform in service.
Testing methods
Ferroxyl test
When ferroxyl (potassium ferricyanide) is in the presence of free iron on the surface of a metal, it reacts and changes to a blue color. This method detects even minimal surface contamination and is highly versatile.
Copper sulfate test
Copper sulfate acts as a less sensitive alternative to the ferroxyl test. When free iron is present, copper deposits create a bronze-colored sheen that persists after rinsing. However, it cannot be used on low-chromium stainless steels or certain other alloys.
How we deliver it
PMI Specialists employs experienced field technicians who perform these tests with precision and effectiveness as part of our field services offering, bringing surface-cleanliness verification to your site.
Free iron testing
Often ordered together
Need to confirm your surfaces are iron-free?
Tell us the alloy and the application. Our field technicians perform the right free iron test on-site and report a clear, defensible result.